The new advocacy group set up by a British activist recently barred from Hong Kong has drawn support from several UK foreign policy heavyweights as it prepares to begin monitoring “worsening” human rights, freedoms and rule of law in the city.

UK-based group Hong Kong Watch, spearheaded by Benedict Rogers, has pledged to raise concerns with the British government and the international community should there be violations of the rights and freedoms enshrined in the Sino-British Joint Declaration and the Basic Law, the city’s mini-constitution.

“We believe that an international NGO to monitor and report on the worsening situation in Hong Kong is much needed and long overdue,” Rogers said in a press release.

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“Based in London, our aim is to be international, a voice in the United Kingdom and other capitals around the world.”

Details about the group emerged three weeks after Rogers, deputy chair of the Conservative Party’s human rights commission, was denied entry to Hong Kong for a private visit, sparking a political row between Britain and China.

Hong Kong Watch, which will be officially established on December 11, has the support of patrons from across the British political spectrum, including former foreign secretary Malcolm Rifkind QC, former Labour shadow foreign minister Catherine West MP, and former Liberal Democrat leader Lord Paddy Ashdown.

“In recent years, there are worrying signs that ‘one country, two systems’ and Hong Kong’s basic freedoms are being eroded,” Ashdown said, referring to the guiding principle safeguarding the city’s freedoms and rights until 2047.

“The Sino-British Joint Declaration is precisely that – a joint declaration signed by both countries and lodged at the United Nations. Hong Kong Watch is being established to monitor, research and advocate in defence of Hong Kong’s freedoms, autonomy and rule of law and to urge both China and Britain to fulfil [their] obligations under the joint declaration.”